U.S. patent number 7,191,806 [Application Number 10/525,465] was granted by the patent office on 2007-03-20 for oil injecting apparatus.
This patent grant is currently assigned to Seiko Instruments Inc.. Invention is credited to Hiromitsu Gotoh, Shinji Kinoshita, Toru Kumagai, Atsushi Ohta, Ryoji Yoneyama.
United States Patent |
7,191,806 |
Yoneyama , et al. |
March 20, 2007 |
Oil injecting apparatus
Abstract
The opening of an oil container 11 for storing oil 12 is sealed
airtight with a cover member 32. A one-sided-bag-shaped fluid
dynamic pressure bearing 10 is seated on an O-ring 25 and fixed
airtight onto the upper surface of a bearing seating 30.
Inanexhaust position with the distal end portion of an injection
tube 36 positioned away from an oil level, the inside of the oil
container 11 is evacuated by a vacuum pump 22 through a
suction/exhaust passage including a suction/exhaust through-hole
17, thus turning the inside of the one-sided-bag-shaped fluid
dynamic pressure bearing (10) into a vacuum. In this state, a
control device drives a moving device to raise the oil container 11
to an injection position and releases the suction/exhaust passage
to the atmosphere. This causes the oil 12 to be injected into the
one-sided-bag-shaped fluid dynamic pressure bearing 10 through an
oil injection passage including the injection tube 36.
Inventors: |
Yoneyama; Ryoji (Chiba,
JP), Kinoshita; Shinji (Chiba, JP),
Kumagai; Toru (Chiba, JP), Gotoh; Hiromitsu
(Chiba, JP), Ohta; Atsushi (Chiba, JP) |
Assignee: |
Seiko Instruments Inc.
(JP)
|
Family
ID: |
32984630 |
Appl.
No.: |
10/525,465 |
Filed: |
March 11, 2004 |
PCT
Filed: |
March 11, 2004 |
PCT No.: |
PCT/JP2004/003192 |
371(c)(1),(2),(4) Date: |
April 18, 2005 |
PCT
Pub. No.: |
WO2004/081439 |
PCT
Pub. Date: |
September 23, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050173196 A1 |
Aug 11, 2005 |
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Foreign Application Priority Data
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Mar 14, 2003 [JP] |
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2003-069770 |
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Current U.S.
Class: |
141/65; 141/59;
141/67; 184/55.1; 141/51 |
Current CPC
Class: |
F16N
37/003 (20130101); F16C 33/103 (20130101); F16C
17/026 (20130101); F16C 33/745 (20130101) |
Current International
Class: |
B65B
31/04 (20060101) |
Field of
Search: |
;141/4-8,51,57,59,65,67,286 ;277/345,400,401 ;384/100,107,114
;184/29,55.1,55.2,57,6.22,58 |
References Cited
[Referenced By]
U.S. Patent Documents
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|
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5112142 |
May 1992 |
Titcomb et al. |
5601125 |
February 1997 |
Parsoneault et al. |
5862841 |
January 1999 |
Wuester, Sr. |
7028721 |
April 2006 |
Bowdoin et al. |
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Foreign Patent Documents
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2004278630 |
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Oct 2004 |
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JP |
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2004278760 |
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Oct 2004 |
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JP |
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Primary Examiner: Maust; Timothy L.
Attorney, Agent or Firm: Adams & Wilks
Claims
The invention claimed is:
1. An oil injecting apparatus comprising: a bearing seating having
a bearing seating surface formed on a front surface thereof and an
oil injection through-passage extending through the bearing seating
from the front surface to a back surface thereof: a cover member
having an injection tube pass-through hole and a suction/exhaust
through-passage; an oil container storing oil to a predetermined
level and sealed with the cover member; a suction/exhaust tube
having one end connected to the suction/exhaust through-passage and
the other end connected to a suction/exhaust device; an injection
tube passing through the injection tube pass-through hole of the
cover member such that the injection tube is capable of vertical
movement while maintaining airtightness, the injection tube having
a lower end projecting into the oil container and an upper end
secured to a lower end of the oil injection through-passage passage
of the bearing seating; a distance changing device which changes a
distance between the bearing seating and the oil container from an
exhaust position in which the lower end of the injection tube is
positioned away from an oil level to an injection position in which
the lower end of the injection tube is submerged into oil; and
bearing fixing means abutting a one-sided-bag-shaped fluid dynamic
pressure bearing into which oil is to be injected, for fixing
airtight the one-sided-bag-shaped fluid dynamic pressure bearing
onto the bearing seating; wherein the one-sided-bag-shaped fluid
dynamic pressure bearing is fixed onto the cover member by the
bearing fixing means, an inside of the one-sided-bag-shaped fluid
dynamic pressure bearing is brought into a vacuum in the exhaust
position by the suction/exhaust device, and then in the injection
position, the suction/exhaust tube is released to an atmosphere to
inject oil in the oil container into the one-sided-bag-shaped fluid
dynamic pressure bearing.
2. An oil injecting apparatus according to claim 1; wherein the
distance changing device vertically moves the bearing seating.
3. An oil injecting apparatus according to claim 1; wherein the
distance changing device vertically moves the oil container
(11).
4. An oil injecting apparatus according to claim 3; wherein the
distance changing device includes a stepping motor.
5. An oil injecting apparatus according to claim 2; wherein the
distance changing device includes a stepping motor.
6. An oil injecting apparatus according to claim 1; wherein the
distance changing device includes a stepping motor.
7. An oil injecting apparatus according to claim 3; wherein the
distance changing device includes a hydraulic motor.
8. An oil injecting apparatus according to claim 2; wherein the
distance changing device includes a hydraulic motor.
9. An oil injecting apparatus according to claim 1; wherein the
distance changing device includes a hydraulic motor.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a U.S. national stage application of
co-pending International Application No. PCT/JP2004/003192, filed
Mar. 11, 2004, claiming a priority date of Mar. 14, 2003, and
published in a non-English language.
TECHNICAL FIELD
The present invention relates to an apparatus for injecting oil
into a one-sided-bag-shaped fluid dynamic pressure bearing by a
vacuum injection method.
The term "one-sided-bag-shaped fluid dynamic pressure bearing" as
used herein refers to a fluid dynamic pressure bearing composed of
bearing components including a shaft and a sleeve, and oil injected
into a minute gap formed between those bearing components, the
fluid dynamic pressure bearing having only one oil injection port
for oil injection into the minute gap.
BACKGROUND ART
As is well known, rolling bearings have been widely adopted for
motors that drive 3.5-inch discs. However, fluid dynamic pressure
bearings are increasingly being adopted for small motors that drive
smaller discs such as 2.5-inch or 1.0-inch discs instead of rolling
bearings.
As shown, for example, in FIG. 6, such a fluid dynamic pressure
bearing includes a flanged shaft 1 serving as a rotary bearing
member, a stepped closed-end sleeve 4 serving as a stationary
bearing member, a thrust retainer plate 5 serving as an annular
cover member, and lubricating oil injected into a minute gap formed
by those members.
The flanged shaft 1 includes a cylinder portion 2 and an annular
flange portion 3 that are integrated with each other. A lower part
of the cylinder portion 2 of the flanged shaft 1 serves as a radial
dynamic pressure bearing cylinder portion, with radial dynamic
pressure generating grooves G1 formed on the outer peripheral
surface thereof. Further, an upper part of the cylinder portion 2
of the flanged shaft 1 serves as a rotor-mounting cylinder portion,
with a rotor-hub-mounting cylinder portion of a small diameter
being formed at its distal end.
The annular flange portion 3 of the flanged shaft 1, which
functions as a disc-shaped thrust plate, has thrust dynamic
pressure generating grooves formed respectively on its upper and
lower surfaces.
The stepped closed-end sleeve 4 has a lower cylinder portion of a
small diameter and an upper cylinder portion of a larger diameter.
An opening with a still larger diameter is formed at the upper end
portion of the upper cylinder portion. The thrust retainer plate 5
is fitted airtight into this opening, whereby the opening of the
stepped closed-end sleeve 4 is sealed airtight with the thrust
retainer plate 5. Formed at the boundary between the small-diameter
lower cylinder portion and the large-diameter upper cylinder
portion is an annular step portion serving as the bottom portion of
the upper cylinder portion.
Between the flanged shaft 1, the stepped closed-end sleeve 4, and
the thrust retainer plate 5, there are formed a cylindrical minute
gap R1, an annular minute gap R2, a cylindrical minute gap R3, an
annular minute gap R4, a cylindrical minute gap R5, and a
disc-shaped minute gap R6. Although somewhat exaggerated in FIG. 6,
the sizes of the minute gaps R1 through R6 range from ten to
several tens .mu. in the case of small and thin fluid dynamic
pressure bearings used in small and thin motors.
It is to be noted that the minute gaps R3 and R6, each functioning
as an oil reservoir, are formed wider than the other minute gaps.
Lubricating oil is injected into these minute gaps by a vacuum
injection method from the annular opening of the cylindrical minute
gap R1.
The inner peripheral surface of the thrust retainer plate 5 forms
an outwardly tapered surface. Accordingly, when seen in cross
section, the cylindrical minute gap R1 formed between the inner
peripheral surface of the thrust retainer plate 5 and the upper
outer peripheral surface of the cylinder portion 2 forms a tapered
gap that is tapered outwardly from the inner to outer portions of
the bearing. The resulting capillary action and surface tension
form a capillary seal portion S that functions to prevent the
lubricating oil from leaking outside of the bearing. Further, the
cylindrical minute gap R3 serves as an oil reservoir for thrust
dynamic pressure bearing, and the disc-shaped minute gap R6 serves
as an oil reservoir for radial dynamic pressure bearing.
As described above, the one-sided-bag-shaped fluid dynamic pressure
bearing shown in FIG. 6 includes the flanged shaft 1, the stepped
closed-end sleeve 4, the thrust retainer plate 5 that is an annular
cover member, and oil for lubrication injected into a minute gap
consisting of the plurality of minute gaps R1 to R6 that are
communicated with each other and formed between those components.
This minute gap defines a one-sided-bag-shaped minute gap, with the
opening of the minute gap R1, which opens to the atmosphere,
serving as the only opening of this minute gap.
Although it is not easy to inject oil into such a
one-sided-bag-shaped fluid dynamic pressure bearing having a
one-sided-bag-shaped minute gap, some injection methods have
already been developed to this end, such as the vacuum injection
methods disclosed in U.S. Pat. No. 5,601,125 (Patent Document 1),
U.S. Pat. No. 5,862,841 (Patent Document 2), and U.S. Pat. No.
5,894,868 (Patent Document 3).
As shown in FIG. 5, for example, a conventional oil injecting
apparatus employing a vacuum injection method includes an oil
container 11 storing an oil 12 to a predetermined level, a cover
member 13 having an oil injection through-passage 15 and a
suction/exhaust through-passage 17, a bellows 11a that is secured
airtight to the back surface of the cover member 13 at one end and
to the opening of the oil container 11 at the other end, an
injection tube 14 whose distal end projects straight into the oil
container 11 and whose other end is connected to the oil injection
through-passage 15, a suction/exhaust tube 16 whose distal end
projects straight into the oil container 11 and whose other end is
connected to one end of the suction/exhaust through-passage 17 of
the cover member 13, a suction/exhaust device connected to the
other end of the suction/exhaust through-passage 17 of the cover
member 13, a moving device that vertically moves the oil container
11 from an exhaust position (FIG. 5 (A)) with the distal end of the
injection tube 14 positioned away from the oil level into an
injection position (FIG. 5(B)) with the distal end of the injection
tube 14 submerged into the oil, and bearing fixing means for fixing
the one-sided-bag-shaped fluid dynamic pressure bearing 10, into
which the oil 12 is to be injected, onto the cover member 13 with
its surface on the oil injection port side being seated on an
O-ring 25.
The suction/exhaust device includes a vacuum pump 22,
suction/exhaust tubes 18, 20, 21, and valves 23, 24. The moving
device includes a stepping motor 27 and an oil container holder 28.
Further, the bearing fixing means forms a part of a holding device
(not shown) holding the cover member 13.
Oil injection is performed as follows with such a conventional oil
injecting apparatus. First, in the exhaust position (FIG. 5(A))
with the distal end of the injection tube 14 positioned away from
the oil level inside the oil container 11, a control device (not
shown) opens the valve 23 and closes the valve 24, and activates
the vacuum pump 22. As this happens, the inside of the oil
container 11 is evacuated through the suction/exhaust tube 16, the
suction/exhaust through-hole 17, and the suction/exhaust tubes 18
and 20; at the same time, the inside of the one-sided-bag-shaped
fluid dynamic pressure bearing 10, which communicates with the
inside of the oil container 11 through the injection tube 14 and
the oil injection through-hole 15, is also evacuated into a
vacuum.
Then, in this state, the control device drives the moving device to
raise the oil container 11, whereby the distal end of the injection
tube 14 is submerged into the oil 12. Subsequently, in this
injection position (FIG. 5(B)), the control device closes the valve
23 and opens the valve 24. As this happens, the inside of the oil
container 11 is communicated with the atmosphere through the
suction/exhaust tube 16, the suction/exhaust through-hole 17, and
the suction/exhaust tubes 18 and 21, and thus turned into the
atmospheric pressure. This causes the oil 12 in the oil container
11 to be injected into the one-sided-bag-shaped fluid dynamic
pressure bearing 10.
Incidentally, the conventional oil injection apparatus described
above is equipped with an extendable part such as a bellows for
vertically moving-the oil container. This bellows is formed of a
rubber material and hence liable to deform when placed in a high
vacuum. Such deformation of the bellows makes it difficult to
maintain a high vacuum degree with good accuracy, resulting in poor
durability. This leads to a problem in that the bellows must be
exchanged frequently in order to maintain this accuracy. In short,
the conventional oil injecting apparatus described above is poor in
operability, resulting in an increase in maintenance cost.
An object of the present invention is to provide an oil injecting
apparatus for injecting oil into a one-sided-bag-shaped fluid
dynamic pressure bearing by a vacuum injection method, the
apparatus providing good operability and low maintenance cost.
DISCLOSURE OF THE INVENTION
To attain the above object, in an oil injecting apparatus for
injecting oil into a one-sided-bag-shaped fluid dynamic pressure
bearing by a vacuum injection method, an injection tube is disposed
so as to be movable while passing through a cover of an oil
container, with airtightness being retained by an O-ring, and the
distance between the oil container and a bearing seating, onto
which the one-sided-bag-shaped fluid dynamic pressure bearing to be
injected with oil is mounted and fixed airtight, is changed to
thereby effect a change from an exhaust position to an injection
position.
That is, an oil injecting apparatus for a one-sided-bag-shaped
fluid dynamic pressure bearing which is designed to attain the
above-mentioned object includes: a bearing seating having a bearing
seating surface formed on a front surface thereof and an oil
injection through-passage extending through the bearing stand from
the front surface to a back surface thereof; an oil container
storing oil to a predetermined level and sealed with a cover member
provided with an injection tube pass-through hole; a
suction/exhaust tube having one end projecting into the oil
container and the other end connected to a suction/exhaust device;
an injection tube passing through the injection tube pass-through
hole of the cover member such that the injection tube is capable of
vertical movement while maintaining airtightness, the injection
tube having a lower end projecting into the oil container and an
upper end secured to a lower end of the oil injection
through-passage of the bearing seating; a distance changing device
which changes a distance between the bearing seating and the oil
container from an exhaust position with the lower end of the
injection tube positioned away from an oil level into an injection
position with the lower end of the injection tube submerged into
oil; and bearing fixing means abutting a one-sided-bag-shaped fluid
dynamic pressure bearing into which oil is to be injected, for
fixing airtight the one-sided-bag-shaped fluid dynamic pressure
bearing onto the bearing seating.
Further, the one-sided-bag-shaped fluid dynamic pressure bearing is
fixed onto the cover member by the bearing fixing means, an inside
of the one-sided-bag-shaped fluid dynamic pressure bearing is
brought into a vacuum in the exhaust position by the
suction/exhaust device, and then in the injection position, the
suction/exhaust tube is released to the atmosphere to inject oil in
the oil container into the one-sided-bag-shaped fluid dynamic
pressure bearing.
The change from the exhaust position to the injection position is
effected through vertical movement of the bearing seating or the
oil container.
The distance changing device is, for example, a stepping motor, a
hydraulic motor, an air cylinder, or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view schematically showing an oil injecting
apparatus for a one-sided-bag-shaped fluid dynamic pressure bearing
according to a first embodiment of the present invention in an
exhaust position.
FIG. 2 is a sectional view schematically showing the oil injecting
apparatus for the one-sided-bag-shaped fluid dynamic pressure
bearing according to the first embodiment of the present invention
in an injection position.
FIG. 3 is a sectional view schematically showing an oil injecting
apparatus for a one-sided-bag-shaped fluid dynamic pressure bearing
according to a second embodiment of the present invention in an
exhaust position.
FIG. 4 are a front view (A) and a side view (B) of the oil
injecting apparatus for a one-sided-bag-shaped fluid dynamic
pressure bearing according to the first embodiment of the present
invention.
FIG. 5 is a sectional view schematically showing a conventional oil
injecting apparatus for a one-sided-bag-shaped fluid dynamic
pressure bearing.
FIG. 6 is a sectional view of a one-sided-bag-shaped fluid dynamic
pressure bearing, showing minute gaps in somewhat exaggerated
sizes.
BEST MODE FOR CARRYING OUT THE INVENTION
As shown in FIGS. 1, 2, and 4, an oil injecting apparatus according
to a first embodiment of the present invention includes a bearing
seating 30 having a bearing seating surface formed on its front
surface and an oil injection through-passage 31 extending through
the bearing seating 30 from this front surface to the back surface
thereof, a cover member 32 provided with an injection tube
pass-through hole 33 and a suction/exhaust through-hole 34, an oil
container 11 storing an oil 12 to a predetermined level and sealed
with the cover member 32, a suction/exhaust tube 18 whose one end
is connected to one end of the suction/exhaust through-hole 34 of
the cover member 32 and whose other end is connected to a
suction/exhaust device, an injection tube 36, a distance changing
device for changing the distance between the bearing seating 30 and
the oil container 11, and bearing fixing means 26 for fixing
airtight onto the bearing seating 30 a one-sided-bag-shaped fluid
dynamic pressure bearing 10, into which oil is to be injected, with
its surface on the oil injection port side being seated and abutted
onto an O-ring 25.
The injection tube 36 with a flat outer peripheral surface passes
through the injection tube pass-through hole 33, which has a flat
inner peripheral surface, in an airtight manner and so as to be
vertically movable, with the lower end of the injection tube 36
projecting into the oil container 11 and the upper end thereof
being secured to the lower end of the oil injection through-passage
31 of the bearing seating 30. The airtightness between the
injection tube pass-through hole 33 and the injection tube 36 is
secured by an O-ring 35 arranged in the injection tube pass-through
hole 33. The airtightness can be further enhanced by providing the
O-ring 35 in two, three, and more stages.
The distance changing device serves to change the distance between
the oil container 11 and the bearing seating 30 so as to bring the
oil injecting apparatus from an exhaust position (FIG. 1) with the
lower end of the injection tube 36 positioned away from the oil
level into an injection position (FIG. 2) with the lower end of the
injection tube 36 submerged into the oil. As shown in FIG. 4, the
distance changing device includes a hydraulic pump 27 and an oil
container holder 28, and raises/lowers the oil container 11 with
respect to the bearing seating 30 whose position is fixed, thereby
changing the distance between the oil container 11 and the bearing
seating 30.
The suction/exhaust device includes a vacuum pump 22,
suction/exhaust tubes 20, 21, and valves 23, 24.
Oil injection is performed as follows with the oil injecting
apparatus according to the first embodiment of the present
invention. First, in the exhaust position (FIG. 1) with the distal
end of the injection tube 14 positioned away from the oil level in
the oil container 11, a control device (not shown) opens the valve
23 and closes the valve 24, and activates the vacuum pump 22. As
this happens, the inside of the oil container 11 is evacuated, and
at the same time, the inside of the one-sided-bag-shaped fluid
dynamic pressure bearing 10, which communicates with the inside of
the oil container 11 through the injection tube 36 and the oil
injection through-passage 31, is also evacuated into a vacuum.
Then, the control device drives the hydraulic pump 27 to move the
oil container 11 into the injection position (FIG. 2), whereby the
lower end of the injection tube 36 is submerged into the oil 12 in
the oil container 11. Subsequently, the control device closes the
valve 23 and opens the valve 24. As this happens, the inside of the
oil container 11 is communicated with the atmosphere through the
suction/exhaust through-hole 34, and the suction/exhaust tubes 18
and 21, and thus turned into the atmospheric pressure. This causes
the oil 12 in the oil container 11 to be injected into the
one-sided-bag-shaped fluid dynamic pressure bearing 10.
As shown in FIG. 3, an oil injection apparatus according to a
second embodiment of the present invention includes a bearing
seating 30 having a bearing seating surface formed on its front
surface and an oil injection through-passage 31 extending through
the bearing seating 30 from this front surface to the back surface
thereof, a cover member 32 provided with an injection tube
pass-through hole 33 and a suction/exhaust through-hole 34, an oil
container 11 storing an oil 12 to a predetermined level and sealed
with the cover member 32, a suction/exhaust tube 18 whose one end
is connected to one end of the suction/exhaust through-hole 34 of
the cover member 32 and whose other end is connected to a
suction/exhaust device, an injection tube 36, a distance changing
device for changing the distance between the bearing seating 30 and
the oil container 11, and bearing fixing means 26 for fixing
airtight onto the bearing seating 30 a one-sided-bag-shaped fluid
dynamic pressure bearing 10, into which oil is to be injected, with
its surface on the oil injection port side being seated and abutted
onto an O-ring 25.
The injection tube 36 with a male thread 36a formed on an
intermediate section thereof passes through the injection tube
pass-through hole 33, which is provided with a female thread 33a
that threadedly engages with the male thread 36a, in an airtight
manner and so as to be vertically movable, with the lower end of
the injection tube 36 projecting into the oil container 11 and the
upper end thereof being secured to the lower end of the oil
injection through-passage 31 of the bearing seating 30. The
airtightness between the injection tube pass-through hole 33 and
the injection tube 36 is secured by an O-ring 35 arranged in the
injection tube pass-through hole 33.
The distance changing device serves to change the distance between
the oil container 11 and the bearing seating 30 so as to bring the
oil injecting apparatus from an exhaust position with the lower end
of the injection tube 36 positioned away from the oil level into an
injection position with the lower end of the injection tube 36
submerged into the oil. The distance changing device includes a
stepping motor (not shown), and rotates and vertically moves the
bearing seating 30, onto which the one-sided-bag-shaped fluid
dynamic pressure bearing 10 to be injected with oil is fixed
airtight, thereby changing the relative distance from the oil
container 11 whose position is fixed.
The suction/exhaust device includes a vacuum pump 22,
suction/exhaust tubes 20, 21, and valves 23, 24.
The oil injecting apparatus employing a vacuum injection method
according to the second embodiment of the present invention is the
same as the oil injecting apparatus employing a vacuum injection
method according to the first embodiment described above, except
for the distance changing means for changing the distance between
the oil container and the bearing seating, onto which the
one-sided-bad-shaped fluid dynamic pressure bearing to be injected
with oil is seated and fixed airtight.
That is, in the first embodiment, as the distance changing means
for effecting a change from the exhaust position to the injection
position, the outer peripheral surface of the injection tube 36 and
the inner peripheral surface of the injection tube pass-through
hole 33 of the cover member 32 are both formed as flat surfaces,
and the oil container 11 is moved without being rotated, thereby
changing the relative distance of the oil container 11 from the
bearing seating 30 onto which the one-sided-bag-shaped fluid
dynamic pressure bearing 10 to be injected with oil is fixed
airtight.
In contrast, in the second embodiment, as the distance changing
means for effecting a change from the exhaust position to the
injection position, the male thread is formed on a part of the
outer peripheral surface of the injection tube 36 and brought into
threaded engagement with the female thread formed on a part of the
inner peripheral surface of the injection tube pass-through hole 33
of the cover member 32, and the bearing seating 30, onto which the
one-sided-bag-shaped fluid dynamic pressure bearing 10 to be
injected with oil is fixed airtight, is rotated for vertical
movement, thereby changing the relative distance of the bearing
seating 30 from the oil container 11 whose position is fixed.
INDUSTRIAL APPLICABILITY
According to the present invention, in the oil injecting apparatus
for injecting oil into a one-sided-bag-shaped fluid dynamic
pressure bearing by a vacuum injection method, the injection tube
is disposed so as to be movable while passing through the oil
container cover, with airtightness being retained by the O-ring,
and the distance between the oil container and the bearing seating,
onto which the one-sided-bag-shaped fluid dynamic pressure bearing
to be injected with oil is fixed airtight, is changed to thereby
effect a change from the exhaust position to the injection
position.
Therefore, as compared with conventional oil injecting apparatuses
equipped with an extendable part such as a bellows, the present
invention can provide an oil injecting apparatus for a
one-sided-bag-shaped fluid dynamic pressure bearing which provides
good operability and low maintenance cost.
* * * * *